Due to the high clinical heterogeneity of epilepsy, there is a critical need for novel metrics aimed at capturing its biological and phenotypic complexity. Frailty is increasingly recognized in various medical disciplines as a useful construct to understand differences in susceptibility to adverse outcomes. Here, we develop a frailty index (FI) for patients with epilepsy (PwE) and explore its association with demographic and clinical features. In this cross-sectional study, we consecutively enrolled 153 PwE from an outpatient epilepsy clinic. Participants were assessed for various health deficits to calculate the FI. Associations between FI and demographic/clinical features, antiseizure medications (ASMs), and patient-reported outcomes were analyzed using general linear models and Spearman correlation. The median age at the time of study visit was 47 years (interquartile range = 33-60), and 89 (58.2%) patients were females. Multiple linear regression revealed that the developed 33-item FI showed an independent association with age, female sex, higher body mass index, family history of epilepsy, intellectual disability, and the number of ASMs used. A robust analysis of covariance showed higher FI levels in patients using cytochrome P450 3A4-inducer ASMs. We found a moderate positive correlation between FI and psychological distress, lower quality of life, and physical frailty, measured by the Hospital Anxiety and Depression Scale, Quality of Life in Epilepsy Inventory-10, and handgrip strength, respectively. Finally, a weak association was observed between higher FI scores and an increased number of epileptic falls. This study highlights the significance of frailty as a comprehensive health measure in epilepsy. It suggests that frailty in this specific population is not only a manifestation of aging but is inherently linked to epilepsy and treatment-related factors. Future research is warranted to validate and refine the FI in diverse epilepsy populations and investigate its impact on specific adverse outcomes in longitudinal studies.